1. Field of the Invention
The present invention relates to a tape cassette for accommodating a magnetic tape capable of recording information such as music and reproducing recorded information.
2. Description of the Related Art
A fixed magnetic head is used as a means for recording and reproducing digital signals of music or the like. It is very important for the digital recording/reproducing system to possess an error rate as low as possible in order to reproduce an original sound faithfully. As disclosed in Japanese Patent Laid-Open Publication No. 3-44857, a head-inserting window of a tape cassette and a pinch roller-inserting window thereof are closed to prevent foreign matter such as dust from penetrating into the tape cassette from the outside. The error rate of the above tape cassette is as large as 2.times.10.sup.-2 when digital signals are recorded and reproduced. This is a fatal defect of the tape cassette in recording/reproducing digital signals. The error rate means the rate of the number of error signals to the number of data read out based on signals recorded on a magnetic tape. The inventors have discovered that a main reason the error rate is great is because in the process of manufacturing a tape or inserting the tape into the tape cassette, fine foreign matter sticks to the surface of the magnetic layer of the tape.
They have also discovered that the magnetic tape is shaven and powders generated by the shaving thereof stick to the surface of the magnetic layer of the tape when it is inserted into a tape cassette recorder to record signals or reproduce recorded signals. This is also one of the reasons why the error rate is great.